1. Filed of the Invention
The present invention relates to a composite high frequency component and a mobile communication device including the same, and more particularly to a composite high frequency component which can be used in plural different mobile communication systems and a mobile communication device including the same.
2. Description of the Related Art
At present, in Europe, as a mobile communication device, a dual band portable telephone has been proposed which can be operated in plural frequency bands, for example, DCS (Digital Cellular System) employing the 1.8 GHz band, and GSM (Global System for Mobile Communications) operative in the 900 MHZ band.
FIG. 14 is a block diagram showing a part of the configuration of a dual band portable telephone as a conventional mobile communication device, illustrating an example of the combination of DCS in the 1.8 GHz band and GSM in the 900 MHZ band. The dual band portable telephone is equipped with an antenna 1, a diplexer 2, and two signal paths, namely, the DCS system 3 and the GSM system 4.
The diplexer 2, for transmission, performs the function of coupling transmitting signals from the DCS system 3 or GSM system 4, and for reception, does that of distributing received signals to the DCS system 3 or GSM system 4. The DCS system 3 is composed of a high frequency switch 3a for separating its transmission section Txd and its reception section Rxd, and a notch filter 3b for attenuating second and third harmonics of DCS. The GSM system 4 is composed of a high frequency switch 4a for separating its transmission section Txg and its reception section Rxg, and a notch filter 4b for attenuating third harmonics of GSM.
The high frequency switches 3a and 4a are separately provided with controlling power supplies Vc 61 and Vc 62 for on-off controlling the switches, respectively.
Hereinafter, the operation of the dual band portable telephone will be described in reference to the case that the DCS system 3 is used as an example. For transmission, with the high frequency switch 3a, the transmission section Txd is turned on, and a transmitting signal from the transmission section Txd is fed to the notch filter 3b. The transmitting signal, passed through the notch filter 3b. is wave-combined in the diplexer 2, and sent through the antenna 1. On the other hand, for reception, a receiving signal, received through the antenna 1, is wave-separated in the diplexer 2. The receiving signal form the antenna 1 is fed to the notch filter 3b. With the high frequency switch 3a, the reception section Rxd is turned on, so that the receiving signal is fed through the notch filter 3b to the reception section Rxd. In the case that the GSM system 4 is used, the transmission and reception are carried out by similar operation.
Further, in Europe, as a mobile communication device, a triple band portable telephone has also been proposed which can be operated in plural frequency bands, for example, by DCS (Digital Cellular System) and PCS (Personal Communication Services) which can be operated in the 1.8 GHz band, and GSM (Global System for Mobile Communications) operative in the 900 MHZ band.
FIG. 15 is a block diagram showing the front end portion of a conventional triple band portable telephone as an example. In this case, as the first and second communication systems operative at adjacent frequencies, DCS and PCS using the 1.8 GHz band, and also, as the third communication system applicable at a different frequency from the first and second communication systems, GSM operative in the 900 MHZ band are employed, respectively.
The front end portion of the triple band portable telephone is provided with an antenna 1a, a diplexer 2a, first through third high frequency switches 3a through 5a, and first and second filters 6a and 7a. The diplexer 2a has the function of coupling transmitting signals by DCS, PCS, or GSM in the case of transmitting, and distributing receiving signals to DCS, PCS, or GSM in the case of receiving. The first high frequency switch 3a switches the transmission section side of DCS and PCS to the reception section side of DCS and PCS and vice versa. The second high frequency switch 4a has the function of switching the reception section Rxd side of DCS to the reception section Rxp side of PCS and vice versa. The third high frequency switch 5a has the function of switching the transmission section Txg side of GSM to the reception section Rxg side thereof and vice versa. The first filter 6a has the function of passing transmitting—receiving signals by DCS and PCS and attenuating second and third harmonics, and the second filter 7a has the function of passing transmitting-receiving signals by GSM and attenuating the third harmonics.
Hereinafter, the operation of the triple band portable telephone, that is, first, the case of DSC will be described. In the case of transmission, with the first high frequency switch 3a, the transmission section Txdp common to that of PCS is turned on, so that a transmitting signal from the transmission section Txdp is fed to the first filter 6a. The transmitting signal passed through the first filter 6a is wave-associated in the diplexer 2a and sent through the antenna 1a. In the case of receiving, a receiving signal received through the antenna 1a is wave-separated in the diplexer 2a. The receiving signal from the antenna 1a is fed to the first filter 6a which is on the DCS and PCS side. With the first high frequency switch 3a, the reception section side is turned on so that the receiving signal passed through the first filter 6a is fed to the second high frequency switch 4a. With the second high frequency switch 4a, the reception section Rxd of DCS is turned on, so that the receiving signal passed through the second high frequency switch 4a is fed to the reception section Rxd of DCS. In the case of PCS used, the transmission and reception is performed by similar operation.
Thereafter, the case of GSM will be described. In the case of transmission, with the third high frequency switch 5a, the transmission section Txg is turned on so that a transmitting signal from the transmission section Txg is fed to the second filter 7a. The transmitting signal passed through the second filter 7a is wave-associated in the diplexer 2a and sent through the antenna 1a. In the case of receiving, a receiving signal received through the antenna 1a is wave-separated in the diplexer 2a. The receiving signal from the antenna 1a is fed to the second filter 7a which is on the GSM side. With the third high frequency switch 5a, the reception section Rxg is turned on, so that the receiving signal passed through the second filter 7a is fed to the reception section Rxg.
However, in the above-described dual band portable telephone which is one of conventional mobile communication devices, the antenna, the diplexer, and the high frequency switches and filters constituting the DCS system and the GSM system are discrete, and are mounted one by one on a circuit board. Accordingly, it is necessary to provide a matching circuit between the diplexer and the high frequency switches in order to assure the matching, the attenuation, or the isolation characteristics. For this reason, the number of the components is increased, causing the increase of the mounting area. As a result, it is necessary to employ a large circuit board. This causes the trouble that the dual band portable telephone (mobile communication device) is increased in size.
Further, in the above-described dual band portable telephone which is one of conventional mobile communication devices, the DCS system and the GSM system are on-off controlled by means of the two separate controlling power supplies only, connected separately to the transmission sides of the high frequency switches. Thus, during the transmission, the high frequency switches of the DCS system and the GSM system are differently operated, which causes the distortion problem with respect to the off-side high frequency switch. Furthermore, it is troublesome that the control of the high frequency switches for the transmission becomes complicate.
Further, in the above-described triple band portable telephone which is one of conventional mobile communication devices, the antenna, the diplexer, and also, the high frequency switches and the filters constituting the DCS system and GSM system are discrete, and mounted on one circuit board. Therefore. in order to assure the matching, the attenuation, and the isolation characteristics of the respective elements, it is necessary to provide a matching circuit between the diplexer and the high frequency switches. Accordingly, the number of the elements is risen, bringing the increase of the mounting area, and thereby, the large circuit board is needed. Thus, there is the problem that the size of the triple band portable telephone (mobile communication device) is large in size.